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@niet grans @anni @frn T. VB. DOCLITTLE, .OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO BRIDGE` i PORT BRASS COMPANY, SAME PLACE.d

Leners 'Patent No. 80,464, ma Juzg. 2s, 186s.

v .IMPROVEMENT IN METHODOF FORMING LAMP-TUBES.

dlgs dgemle nicht in in' tlgrs Etnias tant aan making piatti ilgefsamt TO ALL WHOM ITMAY` CONCERN; v y 4 Be it known that I, T. B. DOOLITTLE, of Bridgeport, of Fairfield county, in the Stateof Connecticut, have invented a certain new and useful Improved Method of Forming Lamp-Tubesf and'I do hereby declare that the following is a full-and exact description thereof, reference being had to the accompanying drawings, making part of this application. k 4

My invention relates to a new and -useful improvement'in the manufacture of dat lamp-tubes.

There are two modes or methods practised of producing this kind of lamp-tubes, one being that in` which a strip of sheet'metal is bent (round a a't mandrel) into the proper shape, having its edges overlapped or interl locked; this kind has ajoint or seam where the edges are brought together. i

In the other method of manufacture, a round seamless tube (which is drawn'outfV after the fashion of drawing cartridge-tubes) is attened out into the required-shape.

Previous to my invention this iiatteuing out or transformation .of the cylindrical tube into a seamless Hat tube,'l1as been effected, generally, by introducing a flat mandrel or former into the cylindrical tube, then pl'acing tube and mandrel between the dies of a press, and, with a blow, flattening the tube down to the thickness of the mandrel; but, inasmuch as the mandrel can only be of a width equal to the diameter o f the cylindrical tube, (before subjected to the operation performed by the iattening-dies,) it follows that thesaid mandrel does not fill the iiattened tube, and therefore cannot act cifectually as a core or former, to give perfect shape tothe v llattened tube.

Another device or means of flattening the `cylindrical tube has been suggested, consisting in introducing into the tube two bars, which are afterward forced apart laterallyyso as to stretch the tube into the Vrequired shape; but this method is objectionablmto a certain extent, (on account of the necessary complication of mechanism involverh) in the manufacture of plain ilat tubes. v

My invention has for its main objects'a simple and effective means of stretching the cylindrical tube into `a fiat one, and consists in transforming the cylindrical tube into a flat one, of given width and thickness, by forcing into it (from opposite ends) wedge-shaped mandrcls or formers, which distend or 4stretch the tube over their opposite exterior edges, as will be presently more fully ekplain'ed. i.

To enable those skilled to make and use my invention, `I will proceed to describe it `more;p articularly, referring by letters to the accompanying drawing, in which- Y YFigure 1 is an elevation of a cylindrical tube (such as is used for the manufacture of flat lamptubes,) and- ,a pair of forming or upsctting-arbors, such as I use.

Figure 2 is a cross-section of same atx z, l.

Figure 3 is an elevation, showing the tube ilattened out by the stretcher-arbors, and

Figure is a cross-section of same at y y. i

At figs. land 2, I have represented the wedge-shaped mandrels A. Bas just entered into the tube C, so as to touch on opposite points at ev e, while at figs. 3 andi-I have shown them as forced along until the tube has l been spread or stretched out to the required size and shape. 'y y Of course vit will be understood thatI propose to employ asuitable mechanism ormachine for manipulating the arbors or stretchingwedges. They will be used practically in connection with an organizedmachine, in which the cylindrical tubes will be fed to them, transformed on them, and then automatically discharged from them; but this machinery will be made the subject-mutter of another applicatioufor Letters Patent, and need not be shown or described in this application.

It will be seen that by introducing two wedge-shaped mandrels, A and B, into acylindrical tube, C, (as seen atfiigs. l and 2,) with their oblique or inclined edges in contact, and forcing them along in the directions indicated by arrows, to the positions (relative to tube B) seen at figs. 3, 4, the said'tube B will be eectually transformed into the desired shape, and this without any complication of parts, -with great facility, and that the Suis-hed fiat tube wil be perfect in shape and size; and it will he understood that it is not essential that .both

wedges, A and B, move togethera and to the same extent, so long as they are brought into the proper relative position, and the tube is moved orheld so as'to be properlynpset or transfortned into the desired shape. The two wedges having a perfect bearing during the whole extent of the; length of the tube, and sliding on each other, and sliding also within the tube',-the upsetting is e'ectedwith great ease, accuracy, and smoothness.

Itwillhe understood that the same mode of operation may be employed 'with wedge-shaped dies which are not of the precise shapein cross-seetion as those shown, to produce a diererlxtly-shaped lamp-tube', and that if deemed expedient, the spreading-mandrels maybe so shaped as to produce a. tube which will be alittle narrower`r at one end than at the other, without departing fromthc gist of my invention, which rests inthe idea of spreadking and shaping the tube by' means of the-wedging-uxandrels forced longitudinally into it, as explained.

Having fully described Vmy invention, so that those skilled in the art can `understand it, what 'I claim as new in the manufacture of attubes from oylindrical'tubes, (or those nearly so,) is i Shaping or transforming the stock by means of wedging-mandrels forced longitudinally, in opposite directions into the tube, to spread it laterally, and shape it, substantially as described.

i* '2: B. DOOLITTLE. [1.. s.]

Witnesses I p J.'N McINTInn, Cms. A. SCOTT'. 

